Northrop N-1M

https://en.wikipedia.org/wiki/Northrop_N-1M

The Northrop N-1M, also known by the nickname "Jeep", was an American
experimental aircraft used in the development of the flying wing concept by
Northrop Aircraft during the 1940s.

Jack Northrop became involved in innovative all-wing aircraft designs in the
late-1920s, with his first Flying Wing being built in the 1928–1930 time period.
That first prototype, the 1929 Flying Wing X-216H, evolved from earlier design
studies. The X-216H had twin rudders with a single horizontal stabilizer running
between them; both rudders were connected by twin booms to the thick, all-wing
blended fuselage. The aircraft had an open cockpit in the center wing section
and single, rear-facing, pusher propeller connected to a piston engine blended
into the all-wing shape. The X-216H was first test flown in 1929 with Edward
Bellande at the controls; the aircraft displayed adequate performance and was
noted for its unique all-metal stressed skin and multi-cellular construction. At
about this same time, Jack Northrop became aware of Walter and Reimar Horten's
prewar record-setting "tailless" flying wing glider designs being tested in
Germany beginning in 1934.

The N-1M was one of a progression of experimental aircraft that further
developed Northrop's all-wing concept. The aircraft was produced in the United
States and was developed during 1939 and 1940 as a flying testbed for the
purpose of proving Jack Northrop's vision of a practical Flying Wing. Built
mostly of specially laminated layers of glued wood, the design of both wooden
wings allowed for easy configuration changes with the central blended fuselage,
which was made of tubular steel. The diminutive, twin-engine test aircraft
served its purpose well, first taking to the skies on 3 July 1941 at Baker Dry
Lake in California.


Role
Flying wing

National origin
United States

Manufacturer
Northrop Corporation

Designer
Jack Northrop

First flight
3 July 1940

Retired
1945

Status
Experimental

Number built
1

Variants
Northrop N-9M

Northrop's Chief Test Pilot Vance Breese flew the N-1M on its maiden flight,
unexpectedly bouncing into the air during a planned high-speed taxi run. He
reported that the aircraft could fly no higher than five feet off the ground.
Flight could only be sustained by maintaining a precise angle of attack, but
Theodore von Kármán solved the problem by making adjustments to the trailing
edges of the elevons. Control of the aircraft was achieved through the use of a
system of elevons and wingtip rudders. The elevons served in tailless type
aircraft both as elevators and ailerons, while split flaps on the downward
angled wingtips took the place of a conventional rudder; they were later
straightened after that angle proved unnecessary during flight testing.

The flight test program continued with Moye W. Stephens, Northrop Test Pilot and
Secretary to the Northrop Corporation, serving as a test pilot. Early tests
showed the N-1M to be satisfactory in stability and control, but overweight and
underpowered. The aircraft's two 65 hp Lycoming 0-145 four-cylinder engines
(buried in the wing to reduce drag) were replaced by two 120 hp six-cylinder
6AC264F2 air-cooled Franklin engines. By November 1941, after having made some
28 flights, Stephens reported that when attempting to move the N-1M about its
vertical axis, the aircraft had a tendency to "Dutch roll." The oscillations
proved to be manageable when adjustments were made to the aircraft's wing
configuration.

The N-1M proved to be basically sound, paving the way for Northrop's later and
much larger Northrop YB-35 and YB-49 aircraft. The pioneering aircraft was then
donated to the United States Army Air Forces in 1945 and was placed in the
storage collection of the National Air Museum the following year. It sat there
for nearly three decades, but was finally brought back to static, non-flying
status, in its final flight configuration, after several years of painstaking
restoration during the 1980s. The N-1M is now on public display at the National
Air and Space Museum's Steven F. Udvar-Hazy Center.

Specifications (N-1M)

General characteristics
Crew: one
Length: 17 ft 11 in (5.46 m)
Wingspan: 38 ft 8 in (11.79 m)
Height: 4 ft 11 in (1.50 m)
Wing area: 350 sq ft (33 m2) (approx)
Gross weight: 3,900 lb (1,769 kg)
Powerplant: 2 × Lycoming O-145 four-cylinder horizontally opposed air-cooled
piston engines, 65 hp (48 kW) each (original engines)
Powerplant: 2 × Franklin 6AC-264F2 six-cylinder air-cooled horizontally opposed
piston engines, 117 hp (87 kW) each (after reengining)

Performance
Maximum speed: 200 mph (322 km/h; 174 kn)
Range: 300 mi (261 nmi; 483 km)
Service ceiling: 4,000 ft (1,200 m)




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